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/* 
函数的arguments对象
 */
 var abc=function(a,b,c,d){
   console.log(arguments);
   console.log(typeof arguments);//Object
   //长度
   console.log(arguments.length);//4
   console.log(arguments.callee);//
   //修改元素
   if(arguments[0]){
      arguments[0]=100;
   }
   console.log(arguments);
   console.log(a);//100,同时也修改了实参
 }
 abc(1,2,3,4);
  </script>
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